Passive Sampling of Munitions Constituents - Revision history

Jhurley: /* Monitoring MC Using Passive Samplers at Underwater Munitions Sites */

2024-04-01T14:51:58Z

‎Monitoring MC Using Passive Samplers at Underwater Munitions Sites

Jhurley at 14:48, 1 April 2024

2024-04-01T14:48:29Z

Admin at 20:36, 27 April 2022

2022-04-27T20:36:23Z

Jhurley at 18:07, 13 May 2020

2020-05-13T18:07:40Z

Jhurley at 15:37, 3 April 2020

2020-04-03T15:37:27Z

Jhurley: /* Monitoring MC Using Passive Samplers at Underwater Munitions Sites */

2020-04-03T14:41:31Z

‎Monitoring MC Using Passive Samplers at Underwater Munitions Sites

Jhurley: /* Controlled Field Demonstration */

2020-04-03T14:06:41Z

‎Controlled Field Demonstration

Jhurley: /* Optimization of POCIS for Munitions Constituents */

2020-04-01T13:49:40Z

‎Optimization of POCIS for Munitions Constituents

Jhurley: /* Technology Overview */

2020-04-01T13:24:33Z

‎Technology Overview

Jhurley: /* Technology Overview */

2020-04-01T13:23:24Z

‎Technology Overview

@@ Line 164: / Line 164: @@
 | colspan="7" style="background-color:white; text-align:left;"| Note: Non-detects expressed as <Method Detection Limit (MDL).
 |}
 ==Related&nbsp;Study:&nbsp;Monitoring&nbsp;MC Using Passive Samplers in Swiss Lakes Near Munitions Dumping Sites==
 Another recent study has also investigated the use of integrative samplers (POCIS and other technologies) to monitor MC in the water column at field sites.  Estoppey et al.<ref name= "Estoppey2019"/> conducted calibration studies using POCIS and the polar version of the Chemcatcher<ref>Charriau, A., Lissalde, S., Poulier, G., Mazzella, N., Buzier, R. and Guibaud, G., 2016. Overview of the Chemcatcher® for the passive sampling of various pollutants in aquatic environments Part A: Principles, calibration, preparation and analysis of the sampler. Talanta, 148, pp.556-571. [https://doi.org/10.1016/j.talanta.2015.06.064 doi: 10.1016/j.talanta.2015.06.064]</ref> in a channel system supplied with continuously refreshed lake water spiked with 9 different MC. Exposure parameters were kept as close as possible to those expected at the study site located at the bottom of two Swiss Lakes where tons of ammunition waste were dumped between 1920 and 1967. Estoppey et al. <ref name= "Estoppey2019"/> demonstrated that analysis of the PES membrane that houses the HLB sorbent is highly important, especially for more hydrophobic MC such as nitroaromatics, as uptake in the PES was substantial, thus delaying the transfer of these compounds to the sorbent. They suggested using a larger pore size for the PES membrane or using a nylon membrane. Estoppey et al.<ref name= "Estoppey2019"/> emphasized the benefit of correcting for flow velocity and recommended concurrent exposure of low-density polyethylene strips loaded with PRCs during POCIS calibration so that mass-transfer coefficients at the water boundary layer (k<sub>w</sub>) could be determined from PRC dissipation, then used to measure flow rates in the field. Integrative TWA concentrations of explosives measured in the lakes were similar for POCIS and Chemcatcher and confirmed results obtained by previous studies based on grab sampling. TWA concentrations were about 0.4 ng/L for RDX and [[Wikipedia: HMX | HMX]] and 0.1 ng/L for [[Wikipedia: Pentaerythritol tetranitrate | pentaerythritol tetranitrate (PETN)]] at the bottom of Lake Lucerne (approximately 200 m below surface). At a similar depth in Lake Thun, TWA concentrations of HMX, RDX, and PETN were lower and most of the time below quantitation limits (0.02 – 0.3 ng/L). In both lakes, nitroaromatic concentrations were below quantitation limits (0.02 – 10 ng/L).

@@ Line 164: / Line 164: @@
 | colspan="7" style="background-color:white; text-align:left;"| Note: Non-detects expressed as <Method Detection Limit (MDL).
 |}
-==Related Study: Monitoring MC Using Passive Samplers in Swiss Lakes Near Munitions Dumping Sites==
+==Related&nbsp;Study:&nbsp;Monitoring&nbsp;MC Using Passive Samplers in Swiss Lakes Near Munitions Dumping Sites==
 Another recent study has also investigated the use of integrative samplers (POCIS and other technologies) to monitor MC in the water column at field sites.  Estoppey et al.<ref name= "Estoppey2019"/> conducted calibration studies using POCIS and the polar version of the Chemcatcher<ref>Charriau, A., Lissalde, S., Poulier, G., Mazzella, N., Buzier, R. and Guibaud, G., 2016. Overview of the Chemcatcher® for the passive sampling of various pollutants in aquatic environments Part A: Principles, calibration, preparation and analysis of the sampler. Talanta, 148, pp.556-571. [https://doi.org/10.1016/j.talanta.2015.06.064 doi: 10.1016/j.talanta.2015.06.064]</ref> in a channel system supplied with continuously refreshed lake water spiked with 9 different MC. Exposure parameters were kept as close as possible to those expected at the study site located at the bottom of two Swiss Lakes where tons of ammunition waste were dumped between 1920 and 1967. Estoppey et al. <ref name= "Estoppey2019"/> demonstrated that analysis of the PES membrane that houses the HLB sorbent is highly important, especially for more hydrophobic MC such as nitroaromatics, as uptake in the PES was substantial, thus delaying the transfer of these compounds to the sorbent. They suggested using a larger pore size for the PES membrane or using a nylon membrane. Estoppey et al.<ref name= "Estoppey2019"/> emphasized the benefit of correcting for flow velocity and recommended concurrent exposure of low-density polyethylene strips loaded with PRCs during POCIS calibration so that mass-transfer coefficients at the water boundary layer (k<sub>w</sub>) could be determined from PRC dissipation, then used to measure flow rates in the field. Integrative TWA concentrations of explosives measured in the lakes were similar for POCIS and Chemcatcher and confirmed results obtained by previous studies based on grab sampling. TWA concentrations were about 0.4 ng/L for RDX and [[Wikipedia: HMX | HMX]] and 0.1 ng/L for [[Wikipedia: Pentaerythritol tetranitrate | pentaerythritol tetranitrate (PETN)]] at the bottom of Lake Lucerne (approximately 200 m below surface). At a similar depth in Lake Thun, TWA concentrations of HMX, RDX, and PETN were lower and most of the time below quantitation limits (0.02 – 0.3 ng/L). In both lakes, nitroaromatic concentrations were below quantitation limits (0.02 – 10 ng/L).

← Older revision		Revision as of 20:36, 27 April 2022
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−	'''~~CONTRIBUTOR~~(S):''' [[Dr. Guilherme Lotufo]] and [[Gunther Rosen]]	+	'''Contributor(s):''' [[Dr. Guilherme Lotufo]] and [[Gunther Rosen]]

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 Passive sampling using integrative samplers enables the monitoring of munitions constituents in underwater environments over timescales of days to months and at ultra-low concentrations. Munitions compounds have an affinity for some resins and polymers that, when submerged for a period of time and corrected for the environment-specific sampling rate, can be used to determine time weighted average ambient water concentrations. This article primarily details the Polar Organic Chemical Integrative Sampler (POCIS), its optimization using laboratory flume and field experiments, and its application at munitions-impacted underwater sites.
 <div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
 '''CONTRIBUTOR(S):'''  [[Dr. Guilherme Lotufo]] and [[Gunther Rosen]]
 '''Key Resource(s)''':

@@ Line 76: / Line 76: @@
 ==Monitoring MC Using Passive Samplers at Underwater Munitions Sites==
-{| class="wikitable" style="float:right; margin-left:30px; margin-right:10px; text-align:center;"
+A POCIS demonstration was conducted in early 2016 at Bahia Salina del Sur (BSS), a former Naval Training Range in Vieques, Puerto Rico, with support provided by Naval Facilities Engineering Command and a multitude of stakeholders, to achieve the following goals:</br>
 |+ Table 1. Summary of TNT and RDX analytical data from POCIS and grab samples collected at Bahia Salina del Sur in January 2016<ref name= "Rosen2017"/>.
 |-
@@ Line 100: / Line 122: @@
 | RDX || 15 || 0 || 0 || -- || 18 || 54
 |-
-| colspan="8" | Note: One POCIS sample was lost during extraction in the laboratory.
+| colspan="8" style="background-color:white; text-align:left;"| Note: One POCIS sample was lost during extraction in the laboratory.
 |}
-A POCIS demonstration was conducted in early 2016 at Bahia Salina del Sur (BSS), a former Naval Training Range in Vieques, Puerto Rico, with support provided by Naval Facilities Engineering Command and a multitude of stakeholders, to achieve the following goals:</br>
+{| class="wikitable" style="float:right; margin-left:30px; margin-right:10px; text-align:center;"
 |+ Table 2. Comparison of MC concentrations in POCIS and grab samples collected near MEC at Bahia Salina del Sur <ref name= "Rosen2017"/>.
 |-
@@ Line 149: / Line 156: @@
 | RDX || T11 || 7 || 24 || <18 || 16.5 || 0.4
 |-
-| colspan="7" | Note: Non-detects expressed as <Method Detection Limit (MDL).
+| colspan="7" style="background-color:white; text-align:left;"| Note: Non-detects expressed as <Method Detection Limit (MDL).
 |}
 ==Related Study: Monitoring MC Using Passive Samplers in Swiss Lakes Near Munitions Dumping Sites==
 Another recent study has also investigated the use of integrative samplers (POCIS and other technologies) to monitor MC in the water column at field sites.  Estoppey et al.<ref name= "Estoppey2019"/> conducted calibration studies using POCIS and the polar version of the Chemcatcher<ref>Charriau, A., Lissalde, S., Poulier, G., Mazzella, N., Buzier, R. and Guibaud, G., 2016. Overview of the Chemcatcher® for the passive sampling of various pollutants in aquatic environments Part A: Principles, calibration, preparation and analysis of the sampler. Talanta, 148, pp.556-571. [https://doi.org/10.1016/j.talanta.2015.06.064 doi: 10.1016/j.talanta.2015.06.064]</ref> in a channel system supplied with continuously refreshed lake water spiked with 9 different MC. Exposure parameters were kept as close as possible to those expected at the study site located at the bottom of two Swiss Lakes where tons of ammunition waste were dumped between 1920 and 1967. Estoppey et al. <ref name= "Estoppey2019"/> demonstrated that analysis of the PES membrane that houses the HLB sorbent is highly important, especially for more hydrophobic MC such as nitroaromatics, as uptake in the PES was substantial, thus delaying the transfer of these compounds to the sorbent. They suggested using a larger pore size for the PES membrane or using a nylon membrane. Estoppey et al.<ref name= "Estoppey2019"/> emphasized the benefit of correcting for flow velocity and recommended concurrent exposure of low-density polyethylene strips loaded with PRCs during POCIS calibration so that mass-transfer coefficients at the water boundary layer (k<sub>w</sub>) could be determined from PRC dissipation, then used to measure flow rates in the field. Integrative TWA concentrations of explosives measured in the lakes were similar for POCIS and Chemcatcher and confirmed results obtained by previous studies based on grab sampling. TWA concentrations were about 0.4 ng/L for RDX and [[Wikipedia: HMX | HMX]] and 0.1 ng/L for [[Wikipedia: Pentaerythritol tetranitrate | pentaerythritol tetranitrate (PETN)]] at the bottom of Lake Lucerne (approximately 200 m below surface). At a similar depth in Lake Thun, TWA concentrations of HMX, RDX, and PETN were lower and most of the time below quantitation limits (0.02 – 0.3 ng/L). In both lakes, nitroaromatic concentrations were below quantitation limits (0.02 – 10 ng/L).
@@ Line 163: / Line 163: @@
 ==Emerging Technology==
 [[Wikipedia: Ethylene-vinyl acetate | Ethylene-vinyl acetate (EVA)]] passive samplers also show promise for quantifying MC in the water column<ref>Warren, J.K., Vlahos, P., Smith, R. and Tobias, C., 2018. Investigation of a new passive sampler for the detection of munitions compounds in marine and freshwater systems. Environmental Toxicology and Chemistry, 37(7), pp.1990-1997. [https://doi.org/10.1002/etc.4143 doi: 10.1002/etc.4143]</ref>. The potential advantages of EVA are that the target compounds come directly into contact with the thermoplastic material that has both hydrophobic and hydrophilic components, eliminating the need for a membrane and with it any potential effects on flow or contaminant interception. The ratio of [[Wikipedia: Vinyl acetate | vinyl acetate]] to [[Wikipedia: Ethylene | ethene]] in the polymer of the sampler can also be manipulated to adsorb specific target chemical types.
 </br>
 </br>

@@ Line 66: / Line 66: @@
 ==Controlled Field Demonstration==
-The POCIS were evaluated for their ability to detect releases at low parts per trillion concentrations in a positive control field study using a known mass of Composition B fragments deployed in an estuarine embayment similar to sites that contain UXO or DMM<ref name= "Rosen2018"/>. This first known field demonstration of the POCIS for MC was conducted in 2014 adjacent to the U.S. Environmental Protection Agency’s (USEPA) Gulf Ecology Division at Santa Rosa Sound, Florida (Figure 7). This site was chosen because it exhibits physical characteristics similar to other underwater sites with MC present (i.e., sandy substrate, estuarine/marine water, and subtropical temperatures). POCIS were also deployed at the site prior to the positive control study, and the results indicated the absence of detectable background MCs. Placement of 15 g of Composition B (RDX and TNT) fragments in a mash bag inside a POCIS canister (Figure 8) suspended just above the sea floor simulated explosive fill material semi-encapsulated inside a munition. For each of 20 sampling locations, three POCIS were placed inside field canisters and deployed for a 13-day period at varying distances, directions, and depths from the “source” canister containing Composition B (Figure 9). POCIS-derived TWA water concentrations for TNT and RDX were low (11–218 ng/L) and decreased with distance from the source (Figure 10), as expected considering the small mass used for the study and the slow dissolution rate of Composition B in water<ref>Lynch, J.C., Brannon, J.M. and Delfino, J.J., 2002. Effects of component interactions on the aqueous solubilities and dissolution rates of the explosive formulations octol, composition B, and LX-14. Journal of Chemical & Engineering Data, 47(3), pp.542-549. https://doi.org/10.1021/je010294j doi: 10.1021/je010294j]</ref>. Both TNT and RDX were below [[Wikipedia: Detection limit | quantitation limits]] (5 - 7 ng/L) 5 m from the source. All grab water samples were below [[Wikipedia: Detection limit | method detection limits]] (120 and 50 ng/L for RDX and TNT, respectively).
+[[File:Lotufo1w2Fig7.png|thumb|left|400px|Figure 7. Controlled field demonstration site, Santa Rosa Sound, Florida]]
 Moderate [[Wikipedia: Biofouling | biofouling]] of POCIS membranes after 13 days led to a subsequent experiment to quantify potential effects of biofouling on the sampling rate for munitions constituents. After biofouling was allowed to occur at the field site, POCIS were transferred to aquaria spiked with munitions constituents (Figure 11). No significant differences in sorbent uptake rates of TNT or RDX due to biofouling were observed over a range of biofouling intensities<ref name= "Rosen2018"/>.
 ==Monitoring MC Using Passive Samplers at Underwater Munitions Sites==

@@ Line 56: / Line 56: @@
 ==Optimization of POCIS for Munitions Constituents==
-[[File:Lotufo1w2Fig5.png|thumb|Figure 5. Flume setup for optimization of POCIS and determination of MC sampling rates.]]
+[[File:Lotufo1w2Fig5.png|thumb|left|600px|Figure 5. Flume setup for optimization of POCIS and determination of MC sampling rates.]][[File:Lotufo1w2Fig6.png|thumb|right|Figure 6. Experimental determination of MC release rate from a perforated munition in a large flume.]]
 The POCIS has recently been demonstrated to be effective for assessment of environmental exposure of MC<ref name= "Rosen2018"/><ref name= "Rosen2017"/><ref name= "belden2015"/><ref name = "Rosen2016"/><ref name= "Lotufo2018"/><ref name= "Lotufo2019"/><ref name= "Estoppey2019"/><ref>Belden, J., Sims, P., Rosen, G., George, R. and Lotufo, G., 2016. Optimization of Integrative Passive Sampling Approaches for Use in the Epibenthic Environment. SERDP Project ER-2542 [[media:2016-Belden-Optimization_of_Integrative_Passive_Sampling_Approaches-ER-2542.pdf| report.pdf]]</ref>. At experimental concentrations of 1 μg/L, [[Munitions Constituents | TNT, aminodinitrotoluenes (ADNTs), and RDX]] accumulated in the POCIS at a linear rate for at least 14 days, with sampling rates between 34 and 215 mL/day<ref name= "belden2015"/>. Calibrations were also performed for [[Munitions Constituents | dinitrotoluenes (DNTs)]]<ref name= "Lotufo2018"/>. Laboratory tank experiments have demonstrated that POCIS can integratively sample water concentrations of MC under widely fluctuating environmental concentrations<ref name= "belden2015"/>.
 As flow rate can have a significant impact on sampling rate, calibration across a range of flow velocities was conducted using MC spiked into a large flume located at the U.S. Army Corps Engineer Research and Development Center (ERDC) in Vicksburg, MS (Figure 5), where flow velocities were precisely controlled<ref name= "Lotufo2018"/>. The flume water (60,000 L) was spiked at 1 μg/L for multiple MC, and POCIS were exposed for 10 days at each of three flow velocities (7, 15, and 30 cm/s). The flume water was drained, refilled, and re-spiked between experiments. Discrete (grab) samples were collected from the flume every other day for the calculation of R<sub>s</sub> under each flow velocity. Sampling rates for TNT varied by up to a factor of two among the three velocities and increased as flow velocity increased. However, the sampling rate for RDX was minimally influenced by flow velocity.  The data has been used to derive velocity-specific R<sub>s</sub> for UWMM sites, as detailed below.
-A follow-up flume study investigated the release of TNT and RDX from Composition B fragments under two realistic exposure scenarios with flow set at 15 cm/s. The first represented the release of MC from fully exposed Composition B and second represented release through a small hole, simulating a breached munition (Figure 6)<ref name= "Lotufo2019"/>. Release of MC through a small hole was approximately 10 times lower than from fully exposed Composition B, demonstrating the strong influence of exposure to flow on release rates. MC in the flume water was quantified using frequent grab sampling and POCIS.  For TNT, POCIS estimated time-weighted-average concentrations were up to 40% higher than those derived from grab samples, while for RDX differences were 6% or less, demonstrating that POCIS provide reliable temporal integration of changing environmental concentrations for common MC.
+A follow-up flume study investigated the release of TNT and RDX from Composition B fragments under two realistic exposure scenarios with flow set at 15 cm/s. The first represented the release of MC from fully exposed Composition B, and the second represented release through a small hole, simulating a breached munition (Figure 6)<ref name= "Lotufo2019"/>. Release of MC through a small hole was approximately 10 times lower than from fully exposed Composition B, demonstrating the strong influence of exposure to flow on release rates. MC in the flume water was quantified using frequent grab sampling and POCIS.  For TNT, POCIS estimated time-weighted-average concentrations were up to 40% higher than those derived from grab samples, while for RDX differences were 6% or less, demonstrating that POCIS provide reliable temporal integration of changing environmental concentrations for common MC.
 For the laboratory studies described above, grab samples (1 L) were analyzed by [[Wikipedia: Solid phase extraction | solid phase extraction (SPE)]] using Oasis HLB SPE columns, eluted with [[Wikipedia: Ethyl acetate | ethyl acetate]], and brought to a final volume of 0.5 ml using procedures optimized by Belden et al.<ref name= "belden2015"/>. The POCIS were disassembled, and the sorbent was rinsed into empty SPE tubes. MCs were eluted with ethyl acetate and brought to a final volume of 0.5 ml. All extracts were analyzed using an Agilent 6850 GC coupled with a 5975C mass selective detector (MSD) using negative chemical ionization with three ions selected for ion monitoring for each analyte. Internal calibration was performed using <sup>13</sup>C-TNT<ref name= "belden2015"/>.

@@ Line 25: / Line 25: @@
 ==Technology Overview==
-[[File:Lotufo1w2Fig3.png|thumb|left|550px|Figure 3. the structure of a POCIS where stainless steel encompasses the PES membranes and the adsorbent in the middle (from Morin et al. 2012 and Seethapathy et al. 2008)<ref name = "Morin2012">Morin, N., Miège, C., Coquery, M. and Randon, J., 2012. Chemical calibration, performance, validation and applications of the polar organic chemical integrative sampler (POCIS) in aquatic environments. TrAC Trends in Analytical Chemistry, 36, pp.144-175. doi: 10.1016/j.trac.2012.01.007 [[media:2012-Morin-Chemical_Calibration_Performance%2C_Validation%2C_and_applications...POCIS.pdf| Author's Manuscript.pdf]]</ref><ref>Seethapathy, S., Gorecki, T. and Li, X., 2008. Passive sampling in environmental analysis. Journal of Chromatography A, 1184(1-2), pp.234-253. [https://doi.org/10.1016/j.chroma.2007.07.070 doi: 10.1016/j.chroma.2007.07.070]</ref>.]]
+[[File:Lotufo1w2Fig3.png|thumb|left|650px|Figure 3. the structure of a POCIS where stainless steel encompasses the PES membranes and the adsorbent in the middle (from Morin et al. 2012 and Seethapathy et al. 2008)<ref name = "Morin2012">Morin, N., Miège, C., Coquery, M. and Randon, J., 2012. Chemical calibration, performance, validation and applications of the polar organic chemical integrative sampler (POCIS) in aquatic environments. TrAC Trends in Analytical Chemistry, 36, pp.144-175. doi: 10.1016/j.trac.2012.01.007 [[media:2012-Morin-Chemical_Calibration_Performance%2C_Validation%2C_and_applications...POCIS.pdf| Author's Manuscript.pdf]]</ref><ref>Seethapathy, S., Gorecki, T. and Li, X., 2008. Passive sampling in environmental analysis. Journal of Chromatography A, 1184(1-2), pp.234-253. [https://doi.org/10.1016/j.chroma.2007.07.070 doi: 10.1016/j.chroma.2007.07.070]</ref>.]]
 The POCIS consists of a receiving phase [[Wikipedia: Sorbent | (sorbent)]] sandwiched between two [[Wikipedia: Polysulfone | polyethersulfone (PES)]] microporous membranes with ~0.1 μm pore size<ref name= "Alvarez2004"/> (Figure 3). The sampler is held together by two stainless steel rings with an interior diameter of 51-54 mm, which provides an exposure surface area of 41-46 cm<sup>2</sup>. The POCIS are available commercially from Environmental Sampling Technologies (EST; St. Joseph, Missouri), and contain the widely used Oasis® hydrophilic-lipophilic balance (HLB) polymer as the sorbent. A variety of sampler holders and canisters have been used to protect the passive samplers in the field. The holder and canister shown in Figure 4 are commercially available from EST.

@@ Line 25: / Line 25: @@
 ==Technology Overview==
 The POCIS consists of a receiving phase [[Wikipedia: Sorbent | (sorbent)]] sandwiched between two [[Wikipedia: Polysulfone | polyethersulfone (PES)]] microporous membranes with ~0.1 μm pore size<ref name= "Alvarez2004"/> (Figure 3). The sampler is held together by two stainless steel rings with an interior diameter of 51-54 mm, which provides an exposure surface area of 41-46 cm<sup>2</sup>. The POCIS are available commercially from Environmental Sampling Technologies (EST; St. Joseph, Missouri), and contain the widely used Oasis® hydrophilic-lipophilic balance (HLB) polymer as the sorbent. A variety of sampler holders and canisters have been used to protect the passive samplers in the field. The holder and canister shown in Figure 4 are commercially available from EST.
-[[File:Lotufo1w2Fig3.png|thumb|right|Figure 3. the structure of a POCIS where stainless steel encompasses the PES membranes and the adsorbent in the middle (from Morin et al. 2012 and Seethapathy et al. 2008)<ref name = "Morin2012">Morin, N., Miège, C., Coquery, M. and Randon, J., 2012. Chemical calibration, performance, validation and applications of the polar organic chemical integrative sampler (POCIS) in aquatic environments. TrAC Trends in Analytical Chemistry, 36, pp.144-175. doi: 10.1016/j.trac.2012.01.007 [[media:2012-Morin-Chemical_Calibration_Performance%2C_Validation%2C_and_applications...POCIS.pdf| Author's Manuscript]]</ref><ref>Seethapathy, S., Gorecki, T. and Li, X., 2008. Passive sampling in environmental analysis. Journal of Chromatography A, 1184(1-2), pp.234-253. [https://doi.org/10.1016/j.chroma.2007.07.070 doi: 10.1016/j.chroma.2007.07.070]</ref>.]]
-[[File:Lotufo1w2Fig4.png|thumb|right|Figure 4.  Sample holder (left) and protective canister for multiple POCIS (right, both supplied by EST).]]
+[[File:Lotufo1w2Fig4.png|thumb|right|450px|Figure 4.  Sample holder (left) and protective canister for multiple POCIS (right, both supplied by EST).]]
 For passive sampling of contaminants, the POCIS are kept immersed in water typically for two weeks to one month. However, depending on the study objectives, deployment times can range from days to months. At the end of the deployment time the POCIS are collected and transported to a laboratory where they are dismantled for collection of the full mass of sorbent. Analytes are extracted from sorbent using standard techniques, typically by organic solvent extraction in a [[Wikipedia: Column chromatography | chromatography column]]. The eluate can be analyzed using instrumental techniques such as [[Wikipedia: Liquid chromatography–mass spectrometry | liquid chromatography coupled with mass spectrometry (LC/MS)]] or by [[Wikipedia: Gas chromatography–mass spectrometry | gas chromatography coupled with MS (GC/MS)]]. More than 300 chemicals with a wide range of commercial and industrial applications have been detected or quantified by the POCIS in laboratory and field testing<ref name = "Morin2012"/>.
@@ Line 34: / Line 36: @@
 {|
-|  || Equation 1:&nbsp;&nbsp;&nbsp;&nbsp; || '''''<big>C</big><sub>w</sub><big> =&nbsp;&nbsp;<sup>N</sup> / <sub>(R</big><sub>s</sub></sub><big><sub>* t) </sub></big>'''''
+|  || Equation 1:&nbsp;&nbsp;&nbsp;&nbsp; || '''''<big>C</big><sub>w</sub><big> =&nbsp;&nbsp;<sup>N</sup> / <sub>(R</big><sub>s</sub></sub><big><sub> * t) </sub></big>'''''
 |-
 | Where:&nbsp;&nbsp;&nbsp;&nbsp;
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 Because of the wide range of field environmental conditions, the biggest challenge facing the use of POCIS has been the lack of a correction method to quantify the effect on the uptake process when field conditions vary from those of the calibration experiment. To overcome this issue, performance reference compounds (PRCs) with experimentally quantified dissipation rates can be spiked into the samplers prior to deployment to account for the effects of field exposure conditions on R<sub>S</sub> values. PRCs should be chosen that do not occur in the environment in which the sampler will be used. The selected PRC should also be significantly but not completely depleted over the planned  deployment period. The mass of PRC lost during deployment is then used to improve the accuracy of the estimated TWA concentration of the analyte of interest. Performance reference compounds have been successfully and widely used to correct for the impact of exposure conditions on hydrophobic passive samplers<ref>Booij, K. and Smedes, F., 2010. An improved method for estimating in situ sampling rates of nonpolar passive samplers. Environmental Science & Technology, 44(17), pp.6789-6794. [https://doi.org/10.1021/es101321v  doi: 10.1021/es101321v ] </ref>. A study by Li et al.<ref name=  "Li2018"/> was the first to demonstrate the reliable use of PRCs for determining TWA concentrations in the field using POCIS.
-POCIS typically exhibit negligible analyte loss rates even when local environmental concentrations of the analyte drop to undetectable levels for some portion of the deployment period. This allows small masses of a chemical of interest from episodic release events to be retained in the device at the end of the deployment period<ref name= "belden2015"/><ref>Harman, C., Thomas, K.V., Tollefsen, K.E., Meier, S., Bøyum, O. and Grung, M., 2009. Monitoring the freely dissolved concentrations of polycyclic aromatic hydrocarbons (PAH) and alkylphenols (AP) around a Norwegian oil platform by holistic passive sampling. Marine Pollution Bulletin, 58(11), pp.1671-1679. [https://doi.org/10.1016/j.marpolbul.2009.06.022  doi: 10.1016/j.marpolbul.2009.06.022 ]</ref><ref>Morrison, S.A. and Belden, J.B., 2016. Calibration of nylon organic chemical integrative samplers and sentinel samplers for quantitative measurement of pulsed aquatic exposures. Journal of Chromatography A, 1449, pp.109-117. [https://doi.org/10.1016/j.chroma.2016.04.072  doi: 10.1016/j.chroma.2016.04.072]</ref><ref>Bernard, M., Boutry, S., Tapie, N., Budzinski, H. and Mazzella, N., 2018. Lab-scale investigation of the ability of Polar Organic Chemical Integrative Sampler to catch short pesticide contamination peaks. Environmental Science and Pollution Research, pp.1-11. [https://doi.org/10.1007/s11356-018-3391-2  doi: 10.1007/s11356-018-3391-2 ]</ref>. Therefore, the POCIS offer an advantageous alternative to traditional sampling methods (e.g. collection of discrete grab samples) at sites where fluctuation in concentrations or low-level concentrations are expected to occur, such as in the vicinity of underwater munitions. The continuous sampling approach of POCIS allows quantification of concentrations in an integrative manner as time weighted averages that are representative of the entire sampling period. The cumulative sampling of contaminant mass over the sampling period also enriches the analyte in the sorbent, which improves detection and quantification of the analyte. As another advantage, the POCIS provides protection of sorbed analytes against decomposition during post-deployment transport and storage<ref>Miège, C., Mazzella, N., Allan, I., Dulio, V., Smedes, F., Tixier, C., Vermeirssen, E., Brant, J., O’Toole, S., Budzinski, H. and Ghestem, J.P., 2015. Position paper on passive sampling techniques for the monitoring of contaminants in the aquatic environment–achievements to date and perspectives. Trends in Environmental Analytical Chemistry, 8, pp.20-26. [[media:2015-Miege-Position_Paper_on_Passive_Sampling_Techniques.pdf| Author's Manuscript]]</ref>.
+POCIS typically exhibit negligible analyte loss rates even when local environmental concentrations of the analyte drop to undetectable levels for some portion of the deployment period. This allows small masses of a chemical of interest from episodic release events to be retained in the device at the end of the deployment period<ref name= "belden2015"/><ref>Harman, C., Thomas, K.V., Tollefsen, K.E., Meier, S., Bøyum, O. and Grung, M., 2009. Monitoring the freely dissolved concentrations of polycyclic aromatic hydrocarbons (PAH) and alkylphenols (AP) around a Norwegian oil platform by holistic passive sampling. Marine Pollution Bulletin, 58(11), pp.1671-1679. [https://doi.org/10.1016/j.marpolbul.2009.06.022  doi: 10.1016/j.marpolbul.2009.06.022 ]</ref><ref>Morrison, S.A. and Belden, J.B., 2016. Calibration of nylon organic chemical integrative samplers and sentinel samplers for quantitative measurement of pulsed aquatic exposures. Journal of Chromatography A, 1449, pp.109-117. [https://doi.org/10.1016/j.chroma.2016.04.072  doi: 10.1016/j.chroma.2016.04.072]</ref><ref>Bernard, M., Boutry, S., Tapie, N., Budzinski, H. and Mazzella, N., 2018. Lab-scale investigation of the ability of Polar Organic Chemical Integrative Sampler to catch short pesticide contamination peaks. Environmental Science and Pollution Research, pp.1-11. [https://doi.org/10.1007/s11356-018-3391-2  doi: 10.1007/s11356-018-3391-2 ]</ref>. Therefore, the POCIS offer an advantageous alternative to traditional sampling methods (e.g. collection of discrete grab samples) at sites where fluctuation in concentrations or low-level concentrations are expected to occur, such as in the vicinity of underwater munitions. The continuous sampling approach of POCIS allows quantification of concentrations in an integrative manner as time weighted averages that are representative of the entire sampling period. The cumulative sampling of contaminant mass over the sampling period also enriches the analyte in the sorbent, which improves detection and quantification of the analyte. As another advantage, the POCIS provides protection of sorbed analytes against decomposition during post-deployment transport and storage<ref>Miège, C., Mazzella, N., Allan, I., Dulio, V., Smedes, F., Tixier, C., Vermeirssen, E., Brant, J., O’Toole, S., Budzinski, H. and Ghestem, J.P., 2015. Position paper on passive sampling techniques for the monitoring of contaminants in the aquatic environment–achievements to date and perspectives. Trends in Environmental Analytical Chemistry, 8, pp.20-26. [[media:2015-Miege-Position_Paper_on_Passive_Sampling_Techniques.pdf| Author's Manuscript.pdf]]</ref>.
 ==Optimization of POCIS for Munitions Constituents==